1. Field of the Invention
The present invention relates generally to an antenna frequency modulating equipment, and more particularly to a PIFA (Planar Inverted-F Antenna) antenna or an H-shape antenna frequency modulating equipment.
2. Description of the Prior Art
With the development of wireless communication, more and more portable electronic devices, such as a notebook, install an antenna system for accessing to Internet. PIFA is a kind of minitype antenna usually used in portable electronic devices. PIFA is featured of compact size, light weight, small occupied space of the portable electronic device, low cost of manufacture, easy to achieve dual frequency bands or multi-bands, good impedance matching, and perfect horizontal polarization and vertical polarization.
It is well known, the radiating and receiving frequency of the antenna is proportional to the length of the radiating portion of the antenna. Designer can calculate the length of the radiating portion according to the working frequency before designing an antenna working at this frequency. However, the length of the radiating portion of the PIFA antenna from the mass production line has windage compared with the required length, and usually the actual length is longer than the required length. It leads to the radiating portion to appear the windage and thus, prevents the antenna from achieving a perfect working frequency. It also affects operating performance of the antenna. The worker must trim the length of the radiating portion of the antenna to desired length before installing the antenna into the notebook or other portable electronic device. On the other hand, the operating frequency of the antenna is infected by inner environment and structure of the notebook or other portable electronic device, so, a PIFA antenna design suitable for a notebook or other portable electronic device is difficult to be operated in another notebook without trimming. However, achieving perfect frequency by trimming the radiating portion of the antenna not only has lower efficiency but also easily makes the antenna become useless because of trimming excessively.
Hence, in this art, a frequency modulating equipment to overcome the above-mentioned disadvantages of the prior art will be described in detail in the following embodiment.